/**
 * @Author 12629
 * @Date 2022/4/6 17:29
 * @Description：
 */
class A {

}
class B extends A {

}
class C extends B {

}

public class TestDemo {
    public static void main(String[] args) {
        A a = new A();
        A a2 = new B();
        A a3 = new C();
    }
}
